The Andes Mountains form the longest mountain chain in the world. Stretching 4,000 miles along the along the western edge of South America, the Andes are known for their volcanoes that can reach more than 20,000 feet above the Pacific Ocean.

The Andes also are known for the Altiplano, a vast plateau of salt lakes and desert nearly as high as Colorado's Rocky Mountains. The air of the Altiplano holds less than two-thirds of the oxygen at sea level.

The Andes host an unusual array of plants and animals specifically designed to cope with high altitude. The best known is the wild guanaco, from which the domesticated llama arose. Llamas have a long history of serving the people of the Andes.

The Incas used llamas for hauling children, gear and crops. Using them as beasts of burden was made easy by the natural curiosity and friendliness of these animals. Llamas also provided meat and high-quality wool.

Kristen Polcyn became familiar with llamas during a series of mission trips to Bolivia. For each of the past several years, Kristen has organized Llama Leap, a 5- kilometer charity run in Seguin (llamaleap.blog spot.com). All proceeds go to Red Vida de Esperanza, which provides medical, educational and church support in rural communities of Potosí, Bolivia.

Potosí's elevation of from 12,500 to 13,500 feet makes it one of the highest cities in the world. At the height of its wealth during Spanish colonial days, thousands of llamas carried silver from the city's legendary mines to seaports far below. Millions of slaves died from the harsh conditions in the mines.

The highlight of Llama Leap is a llama brought by Ray Leslie of Leslie Lane Llamas of La Vernia (www.leslielane llamas.com).

This year, four of these handsome creatures were present, and they all participated in the first few hundred feet of the run. Ray explained that they could have easily outpaced the human runners, but their feet are not designed for running on pavement.

While I was trying to think of a good word to describe llamas, Susan Leslie, Ray's wife, said they seem regal. That certainly captures the spirit of these attractive, curious and friendly animals. They are certainly more regal in appearance and considerably smarter than the sheep we once raised.

You can learn much more about llamas and their kin at archaeology.about.com/od/do mestications/qt/Llama-And- Alpaca.htm, which provided some of the facts in this column. For more about Potosí, see http://wikitravel.org/en/Potos%C3%AD.

Forrest Mims, an amateur scientist whose research has appeared in leading scientific journals, was named one of the “50 Best Brains in Science” by Discover Magazine. His science is featured at www.forrestmims.org. Email him at forrest.mims@ieee.org.